Non-contact or wireless charging systems for electric vehicles or hybrid-electric vehicles have been proposed. Such systems are convenient for charging the vehicles as it is not necessary to manually attach or insert a charging device into the vehicle. Electromagnetic energy is transmitted or communicated from a source resonator typically located in a base unit on a parking surface under the vehicle to a capture resonator attached to the vehicle and typically located on the underside of the vehicle. Because there is the potential for electromagnetic energy to be coupled to unexpected foreign objects proximate to the source resonator and capture resonator, tools, toys, or pets for example, it is advantageous to provide a means to detect such foreign objects.